fitting shower

doing the bathroom up and i am removing an electric shower to replace with a thermostatic mixer.
i have a 36 x 18 cylinder in the airing cupboard on landing and it has a surrey fitting on. the cistern used to be directly above this but i put in the loft replacing it with a 50 gallon cistern,and it sits one metre above the joists, and two metres from shower location
according to triton this cold supply in the loft makes it a low pressure shower only .is this correct?
also as its my first mixer shower and im not sure about this. am i aiming for two 22mm supplies reduced to 15mm just before the mixer valve,at 150mm centres coming out of the stud wall?
i also have a salamander pump, new pearl 75 twin,is this suitable to use in this setup

Sounds ok, although you'll be reducing your pipework sooner if you're connecting the pump up, unless it too has 22mm flexible connectors. But it seems workable. Add isolation either side of the pump, full bore if possible, on both the hot and cold.

nice one davy , the pump is 22mm both sides